I did a little more digging into LED tech and DLP's using LEDs and I found a lead, the main factor in their aging seems to be heat. If the temp is outside of their range it causes stress on something in the LED, and causes it to dim at a quicker pace. A water cooled LED lamp in a DLP has remained consistently bright far longer than any other LED based DLP lamp. (saw it while digging through UMR's posts, don't have the link handy)
With how thin many HDTVs are getting thanks to these things, there isn't much room for the heat they generate to go, mainly due to the lack of airflow. It may only be slightly higher than their intended range in a normal calibration, but even that would be enough to cause problems.
Thicker Backlit models would have fewer issues in theory due to more room to disperse heat, but I can't confirm that. The local dimming array will still cause a slow but steady uneven wear regardless.
I'll continue to try and wrap my head around this issue until definitive proof is found, it's all I can do at this point, try and explain how this might happen.
PSN - Pendragoongp
NNID - Pendragoon
Include your AVS username in the friend request.